Bows and arrows in hand, they arrive a half hour before sunrise and depart a half hour after sunset.

Their mission: Thinning the herd of deer that can end up through the windshields of cars or make local farms their personal smorgasbord.

The Somerset County Park Commission's deer management program was touted a success at its most recent meeting, with commissioners reporting many fewer deer-related motor vehicle accidents and incidents of crop damage.

Park commission secretary-director Raymond A. Brown said about five years ago, representatives from local municipalities, frustrated by the damage caused by deer, asked the commission if they could schedule hunts on county-owned land in their municipalities.

"They have eaten shrubbery; there have been accidents," Brown said. "Clearly, the herds were overpopulated. And that's not healthy for the herds as well."

Dave Dendler, the park ranger manager, estimated that between 150 and 200 deer have been killed during hunts on county parkland this season.

The program is a partnership between the commission, groups of citizen hunters and municipalities.

Not wanting contact between hunters and visitors, the park rangers barricade affected sections of the park system on days when there is a hunt.

Hunting clubs from Bernards and Warren townships, Bridgewater, Branchburg and Peapack-Gladstone are among the participants. Some groups use bows and arrows and others use firearms.

The winter bow season ends Feb. 21.

The hunting groups provide their own insurance.

Brown recalled that in the past, there was talk of the park commission handling the thinning of the deer herd by itself.

But, he noted, there was widespread disagreement over the best way to manage the wildlife and "we didn't want to get caught up in that debate."

By having the towns coordinate their own deer-culling efforts on county land, Brown sees it as a shared service opportunity to solve a mutual problem.

He said at the park system's environmental center, wildflowers are being recorded that had never before been seen.

A Bernards Township survey of residential property damage and related costs during 2003 found that 86 percent of households reported their property sustained deer damage to foundation or landscape plantings over the three previous years, and 73 percent judged the damage "significant." The foundation planting and landscaping damage costs were estimated to be around $13.5 million.

The township is seeing results from its deer-culling efforts, according to a report by Dr. Bill Darrow, chairman of the township's deer management advisory committee.

For the one-year period ending on March 31, 2001, there were 289 deer killed in accidents involving motor vehicles.

For the year that ended on March 31, 2008, there were 191 road kills, a 34 percent decrease.